This article summarizes three principles which should be kept in mind when the heart is examined at necropsy. Principle #1 is to fix the heart in formalin or in some other preserving and firming medium before opening it. Fixation of the specimen before incision allows retention of the three dimensional configuration of the heart and permits more meaningful comparisons between chamber sizes, wall thickness, valve orifice, etc. Principle #2 is to x-ray the fixed heart specimen before opening it. Radiographs reduce the three-dimensional intact heart to a two-dimensional structure and provide additional means of visualizing chamber sizes and wall thicknesses. Principle #3 is that the method chosen to open the heart is determined by the type of cardiac disease that is present or suspected. There is no single way to open the heart, and, in general, hearts with different diseases require different methods of opening. Opening hearts according to the flow of blood, a common practice, is usually the least desirable method of incising hearts.